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Key facts about sexually transmitted infections (STIs)

After declining in the early 2010s, rates of chlamydia, gonorrhea, and syphilis among 15- to 19-year-olds climbed for the second consecutive year in 2016, to 1,929, 380, and 6 cases per 100,000 population, respectively.

While syphilis rates for this age group have returned to 1996 levels, gonorrhea rates decreased by 30 percent and chlamydia rates increased by 78 percent from 1996 to 2016.

Females are much more likely to report having chlamydia or gonorrhea than their male peers, while male youth were more likely than females to report having syphilis.

Non-Hispanic black 15- to 19-year-olds report higher rates of chlamydia, gonorrhea, and syphilis than their Hispanic and non-Hispanic white peers.

Trends in STIs

While there are many types of bacterial, viral, and parasitic infections acquired through sexual activity, this indicator reports on chlamydia, gonorrhea, and syphilis.

Chlamydial infection, as of 2011, had increased by 96 percent since 1996, from 1,081 to 2,121 cases per 100,000. Rates have since decreased, but rose slightly from 2014 to 2016, reaching to 1,929 cases per 100,000.

After decreasing from 1998 to 2004 (from 547 to 422 cases per 100,000), rates of gonorrhea infection increased slightly to 2007 (to 458 cases per 100,000). Since then, rates have mostly declined, hitting a new low in 2014 (325 cases per 100,000). However, there was a 17 percent increase in gonorrhea rates from 2014 to 2016 (to 380 cases per 100,000).

Syphilis infection rates have generally been low from 1996 to 2016, with a high of 6 cases per 100,000 in 1996. While primary and secondary syphilis rates declined from 1996 to 2003, reaching a low of 2 cases per 100,000, they increased from 2003 to 2009, to 5 cases per 100,000. After declining briefly from 2009 to 2011, rates have risen again, reaching 6 cases per 100,000 in 2016 (Appendix 1).

Differences by gender

In 2016, adolescent females were much more likely than males to report a case of chlamydia (3,071 versus 833 cases per 100,000) or gonorrhea (482 versus 281 cases per 100,000). However, adolescent males reported higher rates of syphilis than females in 2016 (9 versus 3 cases per 100,000) (Appendix 1).

Differences by race and Hispanic origin*

Non-Hispanic black youth are much more likely than Hispanic and non-Hispanic white 15- to 19-year-olds to report cases of chlamydia, gonorrhea, and syphilis. For instance, in 2016, rates of chlamydia among non-Hispanic black adolescents were 4,384 per 100,000, compared with 1,081 for Hispanic adolescents and 835 per 100,000 for non-Hispanic white adolescents. Relative racial/ethnic differences were even greater for syphilis (although rates were relatively low for all adolescents), followed by gonorrhea and then chlamydia (Appendix 1).

U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for HIV, STD, and TB Prevention, Division of STD Prevention, Sexually Transmitted Disease Surveillance System.

Background

Definition

Sexually transmitted infections (STIs) refer to a variety of bacterial, viral, and parasitic infections that are acquired through sexual activity. Health care providers are required to report certain STIs under the Centers for Disease Control and Prevention’s surveillance system.